WHO: Processed meat causes cancer

Processed meat has been classified as ‘carcinogenic to humans’ in a recent study by the World Health Organization (WHO)’s cancer agency.

In a scientific literature study by 22 experts from ten countries, the International Agency for Research on Cancer (IARC), part of WHO, evaluated the carcinogenicity of not only processed meat but also red meat.

The IARC working group considered more than 800 studies that investigated associations of more than 12 types of cancer with the consumption of red meat or processed meat in many countries and populations with diverse diets. The most influential evidence came from large prospective cohort studies conducted over the past 20 years.

Processed meat: carcinogenic to humans

Processed meat was classified as carcinogenic to humans (Group 1), based on sufficient evidence in humans that the consumption of processed meat causes colorectal cancer.

In a press release, the WHO's cancer agency describes 'processed meat' as follows:

Processed meat refers to meat that has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavour or improve preservation. Most processed meats contain pork or beef, but processed meats may also contain other red meats, poultry, offal, or meat by-products such as blood. Examples of processed meat include hot dogs (frankfurters), ham, sausages, corned beef, and biltong or beef jerky as well as canned meat and meat-based preparations and sauces.

Red meat: Probably carcinogenic

The expert panel said that consumption of red meat was 'probably carcinogenic to humans (Group 2A)', based on limited evidence that the consumption of red meat causes cancer in humans and strong mechanistic evidence supporting a carcinogenic effect. The experts state: "This association was observed mainly for colorectal cancer, but associations were also seen for pancreatic cancer and prostate cancer."

'Red meat' is described as follows:

Red meat refers to all types of mammalian muscle meat, such as beef, veal, pork, lamb, mutton, horse, and goat.

Meat consumption and its effects

The press release continues to say: "The consumption of meat varies greatly between countries, with from a few percent up to 100% of people eating red meat, depending on the country, and somewhat lower proportions eating processed meat."

The experts concluded that each 50 g portion of processed meat eaten daily increases the risk of colorectal cancer by 18%. Dr Kurt Straif, head of the IARC Monographs programme, was quoted to say: "For an individual, the risk of developing colorectal cancer because of their consumption of processed meat remains small, but this risk increases with the amount of meat consumed."

He continued to say: "In view of the large number of people who consume processed meat, the global impact on cancer incidence is of public health importance."

"Supporting recommendations to limit meat intake"

Dr Christopher Wild, director of IARC, added: "These findings further support current public health recommendations to limit intake of meat."

He added: "At the same time, red meat has nutritional value. Therefore, these results are important in enabling governments and international regulatory agencies to conduct risk assessments, in order to balance the risks and benefits of eating red meat and processed meat and to provide the best possible dietary recommendations."

An article with a summary of the study can be found in the Lancet Oncology. The article is written by Véronique Bouvard, Dana Loomis, Kathryn Z. Guyton, Yann Grosse, Fatiha El Ghissassi, Lamia Benbrahim-Tallaa, Neela Guha, Heidi Mattock and Kurt Straif.

Detailed assessments will be published as Volume 11.4 of the IARC Monographs.